Abstract: Objective: To study the expression of MMP-2、MMP-9、TIMP-2 and infection of bacterial L-forms in ovarian neoplasms and to discuss the clinical significance.Methods: Immunohistochemical staining was used to detect the expression of MMP-2、MMP-9 and TIMP-2 in 120 case of ovarian tumors.Gram's straining was used to examine bacterial L-forms in these tissues.Results: The postive rates of MMP-2、MMP-9 and TIMP-2 were higher in malignant tumors than that in benign ones(P<0.005).The positive rates of MMP-2 and MMP-9 were higher in stage ⅠⅡ than that in stage Ⅲ,Ⅳ,and which increased with the grade (P<0.005).The expression of these two proteinases were higher in patients with lymph node involvement and ascites than those without that(P<0.05 to P<0.005).The positive expression of TIMP-2 was opposite to MMP-2 and MMP-9 (P<0.05 to P<0.005).The positive rate of bacterial L-forms was not higher in malignant tumors than that in benign ones(P>0.05),but it was increased with clinical stage and pathological grade (P<0.005).The expression of L-forms was higher in patients with lymph node involvement and ascites than those without that(P<0.005).Conclusions: In ovarian neoplasms,the abnormal expression of MMP-2、MMP-9、TIMP-2 and positive rate of bacterial L-forms have obvious relationship with clinical stage,pathological grade,lymph node involvement and ascites.Bacterial L-forms is maybe one of the inductive factors of the occurrence of tumor.MMP-2、MMP-9 and bacterial L-forms perhaps have the function of positive cooperativity during the course of the occurrence of ovarian neoplasms.TIMP-2 perhaps accelerate the development of ovarian neoplasms.